PNNL

Abstract

A fundamental understanding of the transition metal dichalcogenide (TMDC)–metal interface is critical for their utilization in a broad range of applications. We investigate how the deposition of palladium, as a model metal, on WTe2(001), leads to the assembly of Pd into clusters and nanoparticles. Using X-ray photoemission spectroscopy, scanning tunneling microscopy imaging, and ab initio simulations, we find that Pd nucleation is driven by the interaction with, and the availability of mobile excess tellurium leading to the formation of Pd-Te clusters at room temperature. Surprisingly, the nucleation of Pd-Te clusters is not affected by intrinsic surface defects, even at elevated temperatures. Upon annealing, the Pd-Te nanoclusters adopt an identical nanostructure and are stable up to ~523 K. Density functional theory calculations provide a foundation for our understanding of the mobility of Pd and Te atoms, preferential nucleation of Pd-Te clusters, and the origin of their annealing-induced monodispersity. These results highlight the role the excess chalcogenide atoms may play in the metal deposition processes. More broadly, the discoveries of synthetic pathways yielding thermally robust monodispersed nanostructures on TMDC’s are critical to the manufacturing of novel quantum and microelectronics devices and catalytically active nano-alloy centers. P. E. E. and Z. D. were supported by the Chemical Dynamics Initiative/Investment, under the Laboratory Directed Research and Development (LDRD) Program at Pacific Northwest National Laboratory (PNNL). Y. W. was supported by the U.S. Department of Energy (DOE), Office of Science (SC), Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program, FWP 47319. P. V. S. was supported by the DOE SC BES, Materials Sciences and Engineering Division through the Award FWP 78705. This research used resources of the National Energy Research Scientific Computing Center, a DOE SC User Facility supported by the SC of the U.S. DOE under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP0024562. PNNL is a multi-program national laboratory operated for the U.S. Department of Energy (DOE) by Battelle Memorial Institute under Contract No. DE-AC05-76RL01830.